Bios

PHOENIX BIOS
Additional information, simulation, and help

Basic Input/Output System (BIOS)

BIOS refers to the firmware code run by a personal computer when first powered on. The primary function of the BIOS is to identify and initiate component hardware, (such as hard drives, floppies, and CDs). This is to prepare the machine so other software programs stored on various media can load, execute, and assume control of the PC^[3]. This process is known as booting, or booting up, which is short for bootstrapping.

The BIOS runs from the PROM, EPROM or, most commonly, flash memory when the computer is powered on. It initializes several motherboard components and peripherals, including:

• The clock generator.
• The processors and caches.
• The chipset (memory controller and I/O controller).
• The system memory.
• All PCI devices (by assigning bus numbers and resources).
• The primary graphics controller.
• Mass storage controllers (such as SATA and IDE controllers).
• Various I/O controllers (such keyboard/mouse and USB).

In computing, firmware is a computer program that is embedded in a hardware device, for example a microcontroller. It can also be provided on flash ROMs or as a binary image file that can be uploaded onto existing hardware by a user.

As its name suggests, firmware is somewhere between hardware and software. Like software, it is a computer program which is executed by a computer. But it is also an intimate and vital part of a piece of hardware, and has little meaning outside of that particular hardware.